looking at the map files from the OSU cells is probably the best starting point for your map file. Its a two step process: first you have to find the layer mappings for your process. Then you plug them into the map file, using the OSU ones as examples.

Most likely you already have a GDS map file for Virtuoso, the foundry should have provided one. Or if you have an Assura techfile, you will also find the mappings there. What you will need is a layer number for each metal layer and each via layer.

Each metal layer has a similar entry. For MOSIS SCMOS, metal1 has number 49. We put all metal1 routes on that layer. In addition, we also put all the text labels on the metal1 layer (the last two lines). That is actually not legal, since it would mean we wanted to produce the shape of text on the mask. But we use this as a trick to keep the label associated with the correct wire shape. Later in Virtuoso we use the "Create Pins from labels" feature to replace all those labels with actual rectangular pins. I would suggest you give this method of label mapping a try, it works very well, especially when you have pins stacked on different layers on top of each other.

On the Virtuoso side you will need a matching map file for the GDS import. Here is a matching line to the example above:

metal1 drawing 49 0

This means that all entries on GDS layer 49 are placed on "metal1 drawing". Most likely you already have this map file from the foundry. In the rare case where you don't have one, then you are free to make up any map file you want to. As long as you use the same layer numbers on the Encounter and Virtuoso side it will work just fine.

How do I create a MAP file for my process so that i can transport my layout from encounter to Virtuoso? I had a look at the one posted at the IIT ASIC design flow tutorial. how do i create a similar one for my process?

I don't have any personal experience with free spice tools, but there seems to be quite a number of them out there. The obvious one is probably the well-known Orcad student demo. Since its PCB oriented I think it is akward to use from an IC perspective, but it is easy to install.

Magic 7 may still be the best layout editor for Mosis SCMOS rules. The OSU library ships with a set of techfiles we converted. The new GDS reader flawlessly reads in Cadence Encounter created GDS files, something Magic 6 wouldn't do.

Depends on which techfile you want to use. For Magic 7 you will need to create many of them using a converter and some manual labor. For Magic 6 all of the classic techfiles are setup. However, most of the sub-180nm techfiles are only created for Magic 7, since it supports those features better than Magic 6.